流化床燃烧棉秆与床料的混合特性及混合质量评判标准

论述了10～100mm长度的棉秆与弱酸性床料的混合流化特性,研究了棉秆长度、床料粒径、配比和流化风速等因素对混合均匀程度的影响.试验结果表明:长度100mm以下特别是50mm左右的棉秆,与粒径为0.6～1mm的床料,在配比为2%(初始质量分数),流化数大于3时,能较均匀地混合流化;但流化数大于7时,混合均匀程度有所降低.棉秆与床料的不同配比对混合均匀程度也有影响,棉秆的质量配比越小,混合得越均匀,所以设计流化床锅炉时流化风速、静止床高要选择合理,否则会影响到密相区的稳定燃烧.提出了秸秆流化床燃烧时,秸秆与床料混合质量的评判标准,并介绍了混合均匀度的概念.在一定的试验条件下,当混合均匀度小于1.4时,秸秆和床料混合比较均匀,能够适合流化床燃烧.

Experimental studies on mixing characteristics and criterion of cotton stalk combustion in fluidized bed

The mixing characteristics of binary mixture of cotton stalk with 10-100 mm length and alternative bed material in a fluidized bed were studied.Experiments on a cold test facility show that long cotton stalk cannot fluidize,and adding bed material can improve the fluidization condition.Effects of length and mass percentage of cotton stalk,diameter of bed material and gas velocity on cotton stalk mixing were investigated.Long cotton stalk can mix well with 0.61 mm alternative bed material as fluidization number ranging between 3-7.The minimum fluidizing velocity of the binary mixture of long cotton stalk and 0.6-1 mm bed material can be obtained by experiments.In addition,the mixing criterion for binary mixture of long cotton stalk and bed material in experimental conditions is presented.When the degree of mixing is less than 1.4,the mixing state of long cotton stalk and bed material can mix well and adapt to fluidized bed combustion.